1. Field of the Invention
The present invention relates to a light-emitting element and particularly to a light-emitting element using Group III nitride compound semiconductor and Group II-Group VI compound semiconductor. The light-emitting element according to the invention can be utilized for a white light source.
2. Description of the Related Art
There is known a light-emitting element or a light-emitting device (LED) of the type which uses a Group III nitride compound semiconductor light-emitting element and a fluorescent substance in combination so that the fluorescent substance can convert the wavelength of a part of light emitted from the light-emitting element to thereby emit light in a color different from the original color of light emitted from the light-emitting element. For example, an LED of the type has been already put into practical use such that the LED of this type uses, in combination, a Group III nitride compound semiconductor light-emitting element for emitting blue light and a fluorescent substance for emitting yellow light when the fluorescent substance is excited by the blue light, with the result that white light can be emitted. The LED of this type is generally formed so that the light-release side of the light-emitting element is coated with a light-transmissive resin-containing a fluorescent substance.
In the related-art LED, a light-emitting element is coated with a fluorescent substance-containing resin (fluorescent substance resin) after the light-emitting element is produced. That is, two steps of producing a light-emitting element and coating the light-emitting element with a fluorescent substance resin are required. Hence, the production process is troublesome and complex as well as the production cost is high.
Moreover, because the light-emitting element is coated with the fluorescent substance resin by means of application, dipping or the like, it is difficult to control the coating thickness of the fluorescent substance resin accurately. For this reason, the amount of the fluorescent substance to be added is apt to vary, so that it is not easy to produce the LED with uniform quality (emission color, emission intensity, and so on).
On the other hand, the field in which LEDs can be used or applied has been widened because the white LED has been already put into practical use. With the advance of widening of the application field, demands for enhancing luminance of LEDs have been made strongly.